// CONST - module-level value declarations as a per-target TEMPLATE.
// const({ threshold: 5 }) | as cfg |> ...use cfg.threshold...
//
// Much simpler than capture:
// - No mutation, so no `captured` branches to transform
// - No runtime struct type conversion needed
// - Just binds constants and flows through
//
// Syntax: const { name: "Claude", count: 42 }   (newline- OR comma-separated)
//
// ARCHITECTURE: `const` is a `[template]` proc over a `source: Source` block —
// NOT a transform. The block is captured WHOLE as a Source (no first-field
// truncation), and the `parse_fields` Zig FILTER (template_processor.zig) splits
// it into `{ name, value }` records. Both the |zig| and |js| variants call that
// SAME filter, so the two lowerings of a const block cannot drift. Each field
// becomes a `const name = value;` declaration; values are emitted verbatim, and
// per-target value shaping (a future `comptime_int` vs `number` split) rides the
// variant boundary — exactly like `if`/`for`. This replaces the old
// transform-+-codegen_utils.koruStructToConstDecls path ("emit Zig and hope").
// `[declaration]`: this keyword template emits DECLARATIONS (names into the
// enclosing scope), not a statement. The emitter splices a declaration flow's
// rendered body directly at container scope (struct members), NOT wrapped in a
// `flow()` function — so sibling flows see the names via Zig container-scope
// lookup. Contrast `if`/`for`, which emit statements into a function body.
~[keyword|declaration] pub tor const { source: Source }